Physico-chemical properties of flesh and <i>in vitro</i> antioxidant activity of flesh and by-products of “Baronne de Rothschild” cv. and “Smooth Cayenne” cv. pineapples produced in Guinea

Pineapple processing generates large quantities of by-products, including the crown, peel, and core, in addition to the edible flesh. This study evaluated the physico-chemical properties of the flesh, as well as the total phenolic content (TPC), total flavonoid content (TFC), and in vitro antioxidant activity of both flesh and by-products from the two main cultivars grown in Guinea: “Baronne de Rothschild” and “Smooth Cayenne.” Fruits harvested at the M3 maturity stage showed significantly higher total soluble solids (TSS) and TSS/titratable acidity (TSS/TA) ratios than those harvested at M2, particularly for “Baronne de Rothschild,” indicating superior sensory quality (p < 0.05). Regardless of cultivar or extraction solvent, the crown and peel exhibited the highest TPC, TFC, and radical scavenging activity measured by ABTS and DPPH assays. Methanolic extracts consistently yielded greater phenolic and flavonoid contents and stronger antioxidant activity than aqueous or ethanolic extracts. The highest TPC reached 2530 ± 25 mg gallic acid equivalents per 100 g crown dry matter. Maximum ABTS and DPPH activities were 81.2 ± 0.7 and 60.6 ± 2.5 µmol Trolox equivalents per gram of crown dry matter, respectively. Antioxidant activity strongly correlated with TPC, confirming crowns and peels as valuable phenolic sources.